This invention relates to an image processing apparatus and method for processing an image signal input from an image sensing device or the like, and to a computer-readable storage medium used in the apparatus and method.
Recent progress in digital signal processing technologies has led to major developments in the video field. In image sensing devices such as digital cameras, signal processing circuitry has been digitized to make possible devices exhibiting no signal deterioration or aging, unlike the case with devices composed of conventional analog circuits.
On the other hand, schemes in which signal processing is implemented not by hardware based upon digital circuits but by software using a CPU have also been proposed. Because the content of signal processing is decided by a program built into a ROM, such schemes make possible adaptive processing in which the content of processing is selected in accordance with the state of the input image.
With the above-described signal processing approach that relies upon digital circuitry, hardware corresponding to all selection candidates must be provided in order to execute adaptive processing. The problem that arises is a great increase in the scale of the circuitry.
With the approach that relies upon software for processing, on the other hand, processing speed is slower than with the hardware-implemented approach and ordinary moving-picture signals (e.g., 720×240 pixels; 60 fields per second) cannot be processed in real time.
The above-mentioned problems encountered with both approaches arise particularly when trying to reduce a decline in image quality due to saturation of the image sensor caused by a subject having a high degree of luminance.